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Page 8 of 12 Mitchell et al. Plast Aesthet Res 2023;10:35 https://dx.doi.org/10.20517/2347-9264.2023.14

Although results are sub-optimal, several studies have shown a reliable return of S2 sensation, which is
meaningful as this is sufficient enough to provide protective sensation [31,32,45] . Ihara et al. demonstrated a
more reliable restoration of this S2 level of sensation following ICN nerve transfers compared to
[32]
supraclavicular sensory transfers .

Graftable C5
In the presence of a graftable C5 nerve root, authors who incorporate this technique prefer nerve autograft
of C5 to the SSN or posterior division of the upper trunk to attempt to restore shoulder stability and
abduction, as opposed to glenohumeral arthrodesis. The remainder of the reconstructive strategy follows as
above with a SAN innervated primary FFMT for elbow flexion/wrist extension and a 5th and 6th ICN
innervated secondary FFMT for elbow flexion/finger flexion, ICN 3-4 to triceps for elbow extension, and a
[7]
sensory ICN 3 to LCMN .
Method 3: contralateral cervical seventh nerve root transfer
Originally described in 1991 by Gu et al. in Shanghai, China, the CC7 transfer has become another viable
[46]
option for reconstruction in PBPI . While ICN nerve transfers are considered effective options, they are
challenging, time-consuming, large dissections with around only 1,300 myelinated axons per donor’s nerve
compared to the limited dissection and 24,000 axons consistent with a CC7 transfer . Moreover, as most
[47]
PBPIs occur in high-energy motor vehicle accidents, damage to the chest wall musculature, rib fractures,
pulmonary contusions, or diaphragm injuries could be contraindications for and preclude the harvest of
ICN.

Elbow flexion
To restore elbow flexion in this technique, the PN is harvested and coapted with the anterior division of the
upper trunk. This aims to reinnervate the MCN motor branches to the biceps and brachialis. The PN can be
exposed overlying the anterior scalene. It should be released as distally as possible prior to entering the chest
cavity. Dissection and isolation of the anterior division of the upper trunk provide the target for this nerve
coaptation.

Good/excellent biceps muscle strength was reported by 80% of patients following PN transfer . A recent
[48]
meta-analysis reported compelling data that PN to MCN transfer is superior to CC7 to MCN transfers in
regards to reconstituting M3 or M4 elbow flexion . One concern over this transfer is the pulmonary
[49]
sequelae of harvesting the PN. However, a series from 2018 demonstrated that this is not a common
[50]
complication, as no patient developed clinical respiratory problems postoperatively .
Shoulder stabilization/abduction
Shoulder abduction may again be accomplished with the transfer of SAN to SSN to reinnervate the
supraspinatus and infraspinatus muscle bellies. As one of the most common nerve transfers in brachial
plexus reconstruction, there are several studies that have reported encouraging outcomes with this transfer.
One study demonstrated good/excellent supraspinatus strength in 79% of patients and good/excellent
infraspinatus strength in 55% of patients . Along with strength, the literature has shown that with
[18]
appropriate coaptation, abduction range of motion recovery can surpass 60 degrees .
[51]
Elbow extension
This review has mentioned several nerve transfer techniques to reinnervate triceps motor function. While
these have shown encouraging results, they are not commonly implemented. Alternatively, it has been an
acceptable option to allow elbow extension to be controlled by gravity alone. Coordinated elbow positioning